Note: Region and former administrative county in northeastern England, along the River Tees and the North Sea. It derives its name from "cliff" land, which refers to escarpment overlooking Vale of Tees. The region is comprised of parts of the historic counties of Durham and Yorkshire to the north and south of the Tees, respectively. It is divided administratively into the unitary authorities of Hartlepool, Stockton-on-Tees, Middlesbrough, and Redcar and Cleveland. At the core of the region is the metropolitan area of Teesside, incorporating the urban areas of Middlesbrough, Stockton-on-Tees, and the western portion of Redcar and Cleveland. Cleveland is the site of many railways, steel, chemical, and petroleum factories.